Hypermetropia: what is it and how can this visual defect be corrected?

By Cristiano Antonino On May 29, 2023

Hypermetropia is a very common and easily correctable visual defect. The ophthalmic term ‘hypermetropia’ refers to a spherical refractive defect in which – light rays produced by objects that appear close or medium close in the field of vision – are focused behind the retina, thus making their viewing blurred

If the optical defect appears slight, the human eye can autonomously and naturally correct it by permanently activating a mechanism called ‘accommodation’.

The accommodation mechanism consists of the natural modification of the globularity of the crystalline lens depending on the proximity or distance of the objects to be focused on.

Light rays emitted by distant objects are focused exactly on the retina, so the crystalline lens will be in an accommodative resting phase, assuming a thinner, finer and more elongated shape.

When, on the other hand, light rays are emitted by objects at a medium or short distance, their focus shifts behind the retina, so the crystalline lens, in order to overcome this problem, increases its curvature surface by becoming more globular.

This greatly increases its power to converge light rays exactly on the retina, so that the objects in question can be seen clearly and sharply.

With increasing age – generally over the age of 40 – the ability of the crystalline lens to actuate the accommodation mechanism is drastically reduced and the hypermetropic subject begins to feel the need for prescription glasses to correct this defect.

Hypermetropia: Symptoms with which it manifests itself

The most common symptoms with which hypermetropia manifests itself – in addition to vision difficulties – are eye fatigue, burning eyes, headaches, misaligned eyes, progressive reduction of vision, blurred vision.

The eye at birth has a shorter axial length than in adulthood and is therefore strongly hypermetropic with a high capacity for accommodation, however, as early as 3 years of age the elongation of the eyeball reduces the hypermetropia to about 2-3 diopters.

However, it can happen that this does not happen completely and the refractive defect known as hypermetropia therefore occurs.

In the child or young person suffering from hypermetropia, the visual impairment is compensated for by the accommodation capacity of the crystalline lens.

In the long run, however, continuous strain may lead to the onset of accommodative asthenopia.

This disorder involves the appearance of symptoms such as fatigue, headache, blurred vision, burning eyes, tearing and a high tendency to develop conjunctivitis.

Accommodative strain stimulating convergence can also cause strabismus.

In adults and the elderly, on the other hand, the accommodation mechanism is no longer as effective, so much so that hypermetropia begins to show the characteristic symptoms of any visual defect: a visual impairment.

This can initially be confused with presbyopia.

Headaches and conjunctivitis may also frequently occur in this case.

Hypermetropia: What causes it and who suffers from it

Hypermetropia can be caused by various factors, first and foremost heredity.

Hypermetropia is manifested when the diameter of the subject’s bulb is shorter than normal; or it can be caused by a superficial curvature of the crystalline lens that is less than normal; or it can be caused by a reduction in the refractive index of the crystalline lens as in diabetes and incipient cataracts, or even in rare cases by the total absence of the crystalline lens, a medical condition known as aphakia.

Hypermetropia: the diagnosis

As soon as the person notices that he or she has vision problems, in particular difficulty viewing nearby objects or reading a normal newspaper page, he or she should consult an ophthalmologist for a diagnostic examination.

During the eye examination, the specialist will carry out a series of tests and examinations using various instrumental techniques.

Among the tests performed, very important will be the test of the visus and refractive state of the eyes, so that the visual process can be assessed in its entirety.

Eye movements, retina and visual acuity will then be examined.

In paediatric age, on the other hand, it is of paramount importance to screen young patients for refractive defects at around 3 years of age for the first time, as information about possible vision problems will be more indirect.

Parents should therefore pay more attention to more subtle signs such as the child’s tendency to approach objects or the presence of more or less obvious eye deviation.

Hypermetropia: how to correct the defect

To date, there is no therapy for hypermetropia; it can only be compensated by the use of positive or convex lenses, or by refractive surgery techniques.

Contact lenses could be the first among the proposed solutions.

These, thanks to their spherical shape, correct the sight defect caused by hypermetropia.

From the point of view of comfort and visual impact, they are definitely the most recommended solution for adult patients suffering from farsightedness.

Before choosing contact lenses, however, it is a good idea to consider all the facets involved in this choice: how often one wishes to change the lenses and how long they should be worn throughout the day.

Corrective spectacles may be more uncomfortable than lenses, but – unlike the latter – they do not carry any contraindications.